Breakfast is eaten within an hour or two after a person wakes in the morning.
Lunch is eaten around mid-day, usually between 11 am and 2 pm. In some areas, the name for this meal depends on its content.
Supper or dinner or tea is eaten in the evening. In some areas, the name for this meal depends on its content, but many English-speakers use "supper" for this meal regardless of size.